In X-ray CT (computed tomography), a fan-shaped X-ray beam is provided from an X-ray source to irradiate an object, and the transmitted X-rays are measured by an X-ray detector including a plurality of detection elements which are arranged in accordance with the expansion of the fan-shaped X-ray beam.
Then, the measurement of transmitted X-rays is performed in multiple view directions while the X-ray source and the detection element array are rotated around the object. Such measurement of transmitted X-rays is called “scanning”. Then, based on the measured data of multiple views obtained by scanning, a tomogram of the object is reconstructed.
There are disclosed techniques for improving spatial resolution of a tomogram in a channel direction by advantageously devising the arrangement of the plurality of detection elements of one X-ray detector.
However, such prior art cannot improve the spatial resolution of a tomogram in a row direction (z-axis direction) of the detection elements.
Moreover, in the prior art, there is no technique available, in a two-tube system, to improve the spatial resolution of a tomogram in a channel direction.